Until the year 2000, there were four recognized oceans: The Pacific, Atlantic, Indian, and Arctic. In the year 2000, the IHO (International Hydrographic Organization) added a new ocean, the Southern Ocean. There are also many Seas. Seas are often partly enclosed by land. The largest ea are the South China Sea, the Caribbean Sea, and the Mediterranean Sea. About 66% of the earth’s surface is covered with water. They are life sources for all animal and plant life and play a crucial role in the biological balance of life on the planet. Increasing pollution has not left them free from toxins. An increase of these pollutants in such an amount that the conditions of the oceans changes physically, chemically and biologically is called Marine pollution. The main cause of Marine pollution or oceanic pollution is the release of waste into the ocean or large bodies of water. The habitats of marine mammals and fish have been destroyed almost completely with pollution responsible for the deaths of fish, mammals and coral. Day by day increasing pollutants like, pesticides, fertilizers, oils and a range of other toxic substances accumulates within fish and through them to man to cause diseases and reproductive disorders. Pollution and warm ocean waters have also degraded coral reefs in several such as Australia and many areas close to the equator. Due to agricultural waste run-off and wastewater, low oxygen dead zones are developed in the ocean near coastlines. Excessive nitrogen has promoted the growth of algae, which promotes toxic organisms like cholera. The industrial wastes loaded with toxic substances such as acids, pesticides, oils, plastics, and wastes of paper, and radioactive materials heavily cause fish dying in different coasts of different nations of the world.One of the most common pollutants of the ocean is raw sewage. Overburden of this sewage causes exponential breeding of algae near the ocean surface preventing the sunlight from reaching deep in the body of water. As a result, photosynthesis is stopped in deep water plants. Plants no longer can absorb carbon dioxide and release oxygen. As a result of this decrease in oxygen level, fish and other animals begin to die. This phenomenon is known as eutrophication. The pollution from nitrogen, are mainly from agricultural run-off. Wastewater has almost tripled the occurrence of dead zones in the past 30 years. Like fertilizers and pesticides other chemicals used for various purposes such as in fire extinguishers, and coolants in refrigerators causes chemical pollution of ocean. Their proportion of amount per weight increase as we increase in the food chain predators. In recent years the use of trisodium nitrilotriacetate (NTA) to make water soft and alkaline, is increased. NTA is biodegradable but forms complex compounds with metals like Mercury, Lead, Cadmium, and Selenium which are poisonous to organic organisms such as fish and other forms of life. Hydrocarbons used for fire extinguishers, and as solvents used in insulation, leak close to 25% into the environment during movement and of this, a 10th finds its way into the ocean and other bodies of water.The most important pollution of the ocean is oil. Oil pollution normally attracts the greatest attention because of its visibility. Every year, approximately 3.5 million tons of oil is released into the world’s oceans and bodies of water. Sources of oil released into the marine environment are often divided into natural, ocean-based and land-based sources with four main categories of pollutant discharges. Natural seeps, discharges during the retrieval of the oil, discharges during the moving of oil, and discharges during the use of oil. These sources result in an estimated average of over 700 million gallons of oil entering our oceans yearly. Less than 10% is from natural seepage from the ocean floor. The remaining 650 million gallons comes from human activities. Offshore drilling, accidental spills and other operations, accounts for 2%. Large tanker spills, account for 5%. Air pollution from cars accounts for 13%. Almost 4 times the amount of oil which comes from the large tanker spills, 19% is released into the ocean from maintenance, which includes boat run-off as well as other ship operations. The greatest cause of oil in our oceans comes from drains and street run-off. Much of this is from inadequate disposal of oil and other toxic substances. An average oil change uses 5 quarts of oil, which alone can contaminate millions of gallons of water in our oceans and ecosystems. Most people have seen the images of oil-covered animals and the large oil spills surrounding the tankers. This oil will spread over large areas often continuing to cause harm for many years. When quantities of oil are sufficient to coat animal fur, the animals cannot stay warm and will ingest the oil while attempting to clean themselves. Many of these oil-coated animals die as a result of ingesting these toxins. Many marine animals that do not die quickly as a result of the oil spill may develop liver disease and reproductive issues.Even in very small quantities, oil will spread, floating on the surface of the water covering vast areas. These thin sheets kill marine larvae, and in turn reduce the number of marine animals and organism capable of surviving such conditions during an oil spill. Thousands of other pollutants also end up in the ocean. More than 2.8 billion gallons of industrial wastewater a day are discharged into the ocean. Heavy metals released from industry, such as mercury and lead, are often found in marine life, many of those often consumed by fish and other organisms. The larger fish such as king mackerel, tilefish, swordfish and shark often contain harmful levels of mercury, which can harm the brain and nervous system.The ship industry has caused a great amount of damage to the marine environment. A typical 3000 passenger cruise liner can produce 255,000 gallons of wastewater and 30,000 gallons of sewage every day. All of this waste is normally released into the ocean. This waste can contain bacteria, medical waste, oils, detergents, cleaners, heavy metals, harmful nutrients and other substances. These substances can be brought back to coastal areas as well as cause damage to the aquatic life in these bodies of water. In 1985 at Haji port of Bombay, about 80,000 fish were found dead due to industrial toxins containing harmful substances. Due to mercury-poisoned fish, about 20,000 people in Japan fell sick and many died in 1978. The disease was given the name Minamata on the name of the city in Japan. Similar diseases from metallic poisoning have already been reported by France, Belgium, England, Holland, Pakistan, and Bangladesh. Industrial substances often contain metallic compounds. For example, Halifax, a small city in eastern Canada, released in its harbor during the 1990s about thirty-three tons of zinc and thirty-one tons of lead a year, with lesser amounts of copper and other metals. When eaten by fish, it accumulates in their tissues and has proved toxic to the fish and to organisms that consume them. The United States began to phase out TBT in 1988, and it was banned internationally in 2008. Industry also produces organic compounds such as polychlorinated biphenyls (PCBs). These accumulate in the fatty tissue of plants and animals low in the food chain, and as they pass through the food web to larger animals, there is an increase in concentration of the substances in their fat, a process known as bioaccumulation. The St. Lawrence River, which drains the Great lakes, has accumulated large amounts of organochlorines, which have compiled in the tissues of Beluga whales. Many animals have tumors and diseases due to these toxic substances. There is mounting evidence that repeated exposure to contaminants causes suppression of the immune responses of marine mammals. Almost all rivers of the world are highly polluted and they carry sewage and toxic substances that is virtually un-treated. In major rivers, excess nutrients can be added as a result of fertilizer run-off, sewage, animal feed-run-off, or air pollution. The dead phytoplankton who consume these particles of toxic substances, sink to the bottom of the water where they are consumed by decomposers. Since these decomposers break down the algae using oxygen, the resulting low oxygen levels can be detrimental to fish health; if dissolved oxygen drops to below 2 mg per 1 fish, mass fish deaths can result. This is known as hypoxia. The areas in which hypoxia have happened are known as Dead Zones. Dead zones have been a factor in the Gulf of Mexico and Chesapeake Bay on the U.S. east coast, and are now spreading to other bodies of water, including the Baltic ocean, Black ocean, and Adriatic ocean. There are now nearly 150 dead zones around the globe with some extending 27,000 miles in diameter. Marine garbage disposal is another major form of oceanic pollution. The world’s oceans are a dumping ground for trash and garbage. Sometimes the garbage includes fishing nets, plastics and household disposables. Garbage in the oceans is a serious issue as fish entangle themselves in fishing nets and animals sometimes eat trash products. There are numerous examples of marine life entangling themselves in fishing nets and dying from starvation of oxygen and food. Marine garbage can enter into animal’s stomach, plastic pop tab rings accidentally strangle animals and so on… Controlling this type of pollution in our oceans, is crucial to successfully eliminating oceanic pollution. Even simple plastic bags can have large impacts within the ocean and other bodies of water. In one case, a deceased sperm whale was found to have a plastic balloon blocking its digestive system preventing it from processing food and died of starvation. Sewage is yet another major source of pollution. Typically, the problem with sewage is that it causes excessive nutrient loading in the ecosystem. Nutrient loading triggers algae blooms in the water leading to the loss of oxygen in the water. After the depletion of oxygen levels, many organisms in the ocean die from being unable to breathe properly. The wastewater released due to washing our clothes, dishes and other household goods is ultimately headed to the ocean. This includes everything from our homes, industrial substances and even chemicals such as fertilizers and paints that we dispose of. Marine beaches serve as natural traps for marine pollution. Globally, the most common materials are plastics, glass, and metal. The major dangers to marine life result from the ingestion of these hazardous materials, which block the stomach, and from entangling, which may cause suffocation. In a survey of U.S. beaches close to urban centers, cigarette butts were the most abundant material, followed by packing items , medical waste, and sewage. A high proportion of this material reached the ocean by way of the sewer system. Even street litter can be washed into surface drains and then to the ocean. Public revulsion at the state U.S. beaches was a key factor in the enactment of stronger environmental protection laws, like the Ocean Dumping Ban of 1988 and the Research and Sanctuaries act of 1972 that prohibited the dumping of sewage and other hazardous materials into the ocean.